P2AA1Alternative Fuel Return Line Valve Control Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2AA1 is the opposite electrical case to P2AA0: the valve drive wire sits at too high a voltage, usually because it touches a battery-fed wire. Where the module switches the ground side, as in the ROUSH CleanTech Gen 4 propane system with its relay-module ground, a line stuck at supply level leaves no voltage across the coil, so the valve cannot be energized at all and stays in its rest position. When the module then turns its transistor on, it may also see an overcurrent and shut the stage off. A wire nipped between harness bundles or a coil whose winding has shorted to its supply pin are the usual finds. Public manufacturer documentation for P2AA1 does not exist; CARB requires output circuit faults to be flagged.
- What you may notice
- Malfunction indicator lamp on
- Return valve cannot be switched and stays in its rest position
- Poor hot starts or switch to the base fuel
- Likely causes
- LikelyControl wire shorted to a battery-fed wire in the harness
- PossibleSolenoid winding shorted to its supply terminal
- PossibleBent or bridged pins in the valve connector
- RareOutput stage in the fuel control module shorted internally
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €40 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.